1. Field of the Invention
The present invention relates to axle casings used in rear axles and more particularly to axle casings used in automobiles and the like.
2. Prior Art
The banjo-shaped axle casing is well known in the art and comprises a substantially disc shaped differential housing and a pair of cylindrical axle housings which project and extend collinearly and outwardly from the outer circumference of the differential housing. Lubricating oil is stored within the differential housing to a level such that the lower portion of the differential gear is constantly submerged in oil.
In the prior art banjo-shaped axle casings, when a horizontal inertial force is applied to the automobile, the lubricating oil within the differential housing flows out from the housing and into the axle housing, causing the differential gear to become insufficiently lubricated. In order to avoid this risk, the prior art banjo-shaped axle casings are provided with a pair of partitions inside the differential housing so as to prevent the lubricant from flowing into the axle housing in large amounts when a horizontal inertial force acts upon the automobile. Each of the partitions has a hole disposed at the center thereof for passing the axle therethrough. In addition, a plurality of small holes or slits are disposed about the rim of the outer circumference of the partition. The partitions are fixed, at the rim of the outer circumference, to the inside wall of the axle casing by welding. The aforementioned small holes and/or slits are provided so as to permit the lubricant which has flowed into the axle housings to return to the differential housing therethrough.
To make a rear axle assembly employing the prior art banjo-shaped axle casing as described hereinabove, (i) the axle casing is made by welding (the method of producing the axle casing itself is well known in the art and therefore will not be discussed herein); (ii) the partitions are inserted into the axle casing through a cap opening provided at the front of the differential housing; (iii) each partition is positioned at a predetermined position; (iv) the rim of the outer circumference thereof is welded to the inside wall of the axle casings; and (v) the inside of axle casing is cleansed.
The prior art banjo-shaped axle casings manufactured according to the above described process steps has the following shortcomings:
1. Since the positioning of the partitions as well as the welding of the partitions to the inside wall of the axle casings must be done in a dark, confined space of the axle casing, the accuracy and efficiency of the operations are adversely affected.
2. Scales and other particles that peel off from the welded portion and the inside wall of the axle casing during the welding operation and subsequent cleansing operations, clog up the small holes in the partitions and prevent the lubricating oil from flowing back into the differential housing during operation thereby resulting in an oil deficient differential and early differential failure. Moreover, scales and the like may cause damage to the differential gear.
The present invention solves these drawbacks and provides an improved banjo-shaped axle casing which is simple to make and whose differential is free from the risk of being insufficiently lubricated.